First confirmed! There is a "plunge zone" around a black hole | Technology Weekly

Compiled by Zhou Shuyi and Wang Xiang

Crows can count loudly

Crows can count up to four using their calls, given visual and auditory cues, a new study shows.

Counting is a human gift. We associate numbers of things with specific symbols (such as 6) and make sounds - liù. Before we master this ability, young children count verbally, such as seeing three apples, they may say: "One, two, three", or "one, one, one".

Previous studies have shown that several animals can distinguish between different quantities of objects. However, it was not clear whether non-human animals can deliberately make a specific number of sounds to "count".

Small-billed crow | Source: Andreas Nieder

The researchers trained three small-billed crows (Corvus corone) to respond to visual or auditory cues with one to four calls (for example, if the colored number "3" is displayed on the screen, or a drum sound is played, the crow should call three times), after which the crow will peck a button to confirm that the "answer is complete." If the answer is correct, they will receive a food reward. After thousands of training sessions, the crows learned to follow the prompts and call the correct number of times. The researchers believe this shows that they understand the logic of the task.

The crow counted "four, three, two, one" in sequence, playing a special prompt tone each time, and then pecking the button to confirm ("dong") when it finished answering. | Source: DIANA LIAO

However, crows also make mistakes. This is usually when the experiment is repeated many times and they are asked to count "3" or "4". Researchers say they like "1" and really hate "4". Sometimes, crows will not say a word when they encounter "4" and will just peck the button to skip it.

Audio analysis shows that crows need a certain amount of "reaction time" before they can "count" vocally, and they react slower to counting "4" than "1". The study believes that this is because they need time to plan the number of times they make sounds. In addition, it was found that the acoustic characteristics of the crow's first call can be used to predict the number of subsequent calls; and the acoustic characteristics of each call are different, which can indicate how many the crow has "counted" - if the crow "counts" incorrectly, the researchers can "hear" it.

The researchers stress that this behavior of crows is not counting as we typically understand it (which requires understanding the symbolic meaning of numbers), but it may be the prototype of this ability.

The existence of a "plunge zone" around a black hole has been confirmed for the first time

Einstein was right again. A new study confirms one of Einstein's key predictions about black holes: the existence of a "plunging region" around black holes, where matter stops circling the black hole and falls directly into it. In addition, this region also observes the strongest gravity yet detected in the Milky Way.

The black hole draws matter from the companion star, forming an accretion disk. (Conceptual image) | Image credit: NASA / CXC / M. Weiss

General relativity states that once particles get close enough to a black hole, they no longer follow elliptical orbits, but instead they plunge toward the black hole at nearly the speed of light. For decades, astrophysicists have debated whether the so-called "plunge zone" can be detected.

The researchers used X-ray data collected by NASA's NuSTAR and NICER to observe the black hole X-ray binary MAXI J1820+070, which is about 10,000 light-years away from the solar system. The system consists of a star and a black hole. The outer edge of the star continuously strips away matter to form an accretion disk, which eventually falls into the black hole. The results showed that the observational data is inconsistent with the traditional model, and supports the prediction that matter falls into the plunge zone.

The world's first live pig liver transplant was successful, and the patient is now walking

According to the First Affiliated Hospital of Anhui Medical University, the hospital recently completed the world's first clinical assisted xenotransplantation of a living human, successfully transplanting a transgenic pig liver into a patient with severe liver cancer. This is also the fifth clinical xenotransplantation in the world.

According to reports, the operation was completed on May 17 by the team of Professor Sun Beicheng from the First Affiliated Hospital of Anhui Medical University and the team of Professor Wei Hongjiang from Yunnan Agricultural University. The patient did not experience hyperacute and acute rejection after the operation, and the coagulation system was not impaired. The transplanted pig liver secreted about 200 ml of golden bile every day. CT and B-ultrasound confirmed that the blood flow in the hepatic artery, portal vein, and hepatic vein of the transplanted pig liver was normal. At present, the patient has been able to walk freely, and many indicators such as liver function have returned to normal.

Source: The First Affiliated Hospital of Anhui Medical University

The patient was a 71-year-old with giant right lobe liver cancer. When interventional treatments were ineffective and rupture could occur at any time, the team transplanted a 514-gram liver from a 10-gene-edited pig (11 months old, 32 kg in weight, male) into the patient's right hepatic fossa after obtaining full informed consent from the patient's family. The operation was very successful and bile was secreted immediately.

The 10 gene-edited pigs used in this transplantation came from the Yunnan Key Laboratory of Miniature Pig Gene Editing and Xenotransplantation of Yunnan Agricultural University. Through gene editing, hyperacute and acute rejection reactions, coagulation dysfunction, etc. in xenotransplantation can be effectively avoided.

Produced by: Science Popularization China

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